I spent Carnivale in Valletta Malta. And while it's not a big place, there were still crowds of people out on the street all evening and night for 5 days running. And I'm sure tourists, like my group, came in from outside Malta for the Carnivale.
The outbreak in No. Italy was getting underway (and in fact Milan's Carnival was canceled). And there were a few times where we looked around and then said to each other that this would be a real opportunity for viral transmission if just one person was infected. And there I was just in from China (though Shanghai was pretty safe and I had been under voluntary lockdown for 3 weeks already).
I thought about Mardi Gras in New Orleans and hoped the virus hadn't penetrated that far yet, because that would of course be a potential hotspot.